Upstream ios/web/web_state/ui support classes

ios/web/web_state/ui/web_view_js_utils.mm

Index: ios/web/web_state/ui/web_view_js_utils.mm
diff --git a/ios/web/web_state/ui/web_view_js_utils.mm b/ios/web/web_state/ui/web_view_js_utils.mm
new file mode 100644
index 0000000000000000000000000000000000000000..7bc4ecb7ff36f78166b39fb4af9ba0cccf72dd0a
--- /dev/null
+++ b/ios/web/web_state/ui/web_view_js_utils.mm
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+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/web/web_state/ui/web_view_js_utils.h"
+
+#import <UIKit/UIKit.h>
+#import <WebKit/WebKit.h>
+
+#include "base/ios/weak_nsobject.h"
+#include "base/logging.h"
+#include "base/mac/scoped_nsobject.h"
+
+namespace {
+
+// Converts result of WKWebView script evaluation to UIWebView format.
+NSString* UIResultFromWKResult(id result) {
+  if (!result)
+    return @"";
+
+  CFTypeID result_type = CFGetTypeID(result);
+  if (result_type == CFStringGetTypeID())
+    return result;
+
+  if (result_type == CFNumberGetTypeID())
+    return [result stringValue];
+
+  if (result_type == CFBooleanGetTypeID())
+    return [result boolValue] ? @"true" : @"false";
+
+  // TODO(stuartmorgan): Stringify other types.
+  NOTREACHED();
+  return nil;
+}
+
+}  // namespace
+
+namespace web {
+
+void EvaluateJavaScript(UIWebView* web_view,
+                        NSString* script,
+                        JavaScriptCompletion completion_handler) {
+  base::WeakNSObject<UIWebView> weak_web_view(web_view);
+  dispatch_async(dispatch_get_main_queue(), ^{
+    NSString* result =
+        [weak_web_view stringByEvaluatingJavaScriptFromString:script];
+    if (completion_handler)
+      completion_handler(result, nil);
+  });
+}
+
+void EvaluateJavaScript(WKWebView* web_view,
+                        NSString* script,
+                        JavaScriptCompletion completion_handler) {
+  DCHECK([script length]);
+  // __block qualifier ensures that web_view_completion_handler is correctly
+  // captured by itself.
+  __block void (^web_view_completion_handler)(id, NSError*) = nil;
+  // Do not create a web_view_completion_handler if no |handler| is passed to
+  // this function. This results in no creation of an unnecessary block.
+  if (completion_handler) {
+    // WKWebView crashes on deallocation when it flushes scripts that did not
+    // finish the execution but have |completion_handler|. Passing
+    // |completion_handler| ownership to the block itself and keeping it alive
+    // until it's executed fixes the crash. No memory leak is expected since
+    // |completion_handler| is always executed even if WKWebView is deallocated.
+    // https://bugs.webkit.org/show_bug.cgi?id=140203
+    web_view_completion_handler = [^(id result, NSError* error) {
+      completion_handler(UIResultFromWKResult(result), error);
+      [web_view_completion_handler autorelease];
+    } copy];
+  }
+  [web_view evaluateJavaScript:script
+             completionHandler:web_view_completion_handler];
+}
+
+}  // namespace web